Guidewire with smoothly tapered segment

ABSTRACT

A guidewire for intraluminal advancement of a medical device within a patient which has an elongate core member with a flexible body member disposed on a distal section thereof. In one embodiment, the distal section of the elongate core member has at least one flexible segment with at least one pair of opposed tapered or parallel faces. Preferably the flexible segment with the tapered or parallel faces is disposed at the distal end of the elongate core and forms a shapable segment.

BACKGROUND OF THE INVENTION

[0001] This invention relates to the field of guidewires for advancingintraluminal devices such as stent delivery catheters, balloondilatation catheters, atherectomy catheters and the like within bodylumens.

[0002] In a typical percutaneous coronary procedure, a guiding catheterhaving a pre-formed distal tip is percutaneously introduced into apatient's peripheral artery, e.g. femoral or brachial artery, by meansof a conventional Seldinger technique and advanced therein until thedistal tip of the guiding catheter is seated in the ostium of a desiredcoronary artery. A guidewire is first advanced by itself through theguiding catheter until the distal tip of the guidewire extends beyondthe arterial location where the procedure is to be performed. Then arail type catheter, such as described in U.S. Pat. No. 5,061,395 (Yock)and the previously discussed McInnes, et al., is mounted onto theproximal portion of the guidewire which extends out of the proximal endof the guiding catheter which is outside of the patient. The catheter isadvanced over the guidewire, while the position of the guidewire isfixed, until the operative means on the rail type catheter is disposedwithin the arterial location where the procedure is to be performed.After the procedure the intravascular device may be withdrawn from thepatient over the guidewire or the guidewire repositioned within thecoronary anatomy for an additional procedure.

[0003] A guidewire may also be used in conjunction with the delivery ofan intracorornary stent. One method and system involves disposing acompressed or otherwise small diameter stent about an expandable membersuch as a balloon on the distal end of a catheter, advancing thecatheter through the patient's vascular system over a guidewire untilthe stent is in the desired location within a blood vessel and thenexpanding the expandable member on the catheter to expand the stentwithin the blood vessel. The dilated expandable member is thencontracted and the catheter withdrawn, leaving the expanded stent withinthe blood vessel, holding the passageway thereof open. This lattermethod and system can be used concurrently with balloon angioplasty orsubsequent thereto.

[0004] Further details of guidewires, and devices associated therewithfor various interventional procedures can be found in U.S. Pat. No.4,748,986 (Morrison et al.); U.S. Pat. No. 4,538,622 (Samson et al.);U.S. Pat. No. 5,135,503 (Abrams); U.S. Pat. No. 5,341,818 (Abrams etal.); and U.S. Pat. No. 5,345,945 (Hodgson, et al.) which are herebyincorporated herein in their entirety by reference thereto.

[0005] Conventional guidewires for angioplasty, stent delivery,atherectomy and other intravascular procedures usually comprise anelongate core member with one or more tapered segments near the distalend thereof. A flexible body member, such as a helical coil or a tubularbody of polymeric material, is typically disposed about the distalportion of the core member. A shapable member, which may be the distalextremity of the core member or a separate shapeable ribbon which issecured to the distal extremity of the core member extends through theflexible body and is secured to the distal end of the flexible body bysoldering, brazing or welding, or an adhesive in the case of polymericflexible bodies which forms a rounded distal tip. The leading tip ishighly flexible and will not damage or perforate the vessel and theportion behind the distal tip is increasingly stiff which bettersupports a balloon catheter or similar device.

[0006] The shapeable member or ribbon of a typical guidewire is a smalldiameter wire which has been flattened to a constant transverse profile.Flattening of the shapable member facilitates the shapability of themember, however, a shapable member having a constant transverse profileor flexibility can be subject to prolapse during use. Prolapse occurswhen the shapable member gets bent back on itself in a constrained lumenand is difficult to straighten out with proximal manipulation. Onemethod of preventing prolapse or reducing the occurrence thereof is tohave increased stiffness at a proximal end of a shapable member. Thishas been done with incremental steps in the shapable member with thinnermore flexible steps distally creating greater flexibility distally.However, the use of incremental steps can cause abrupt changes inflexibility of the shapable member which can be detrimental to smoothtracking and performance of the guidewire. What has been needed is aguidewire with a shapeable member at the distal section that iscontinuously varied in flexibility and maintains a shapeable character.The present invention satisfies these and other needs.

SUMMARY OF THE INVENTION

[0007] The present invention is directed to a guidewire having anelongate core member with a proximal section and a distal section. Thedistal section preferably has at least one flexible segment with two ormore opposed faces that are parallel or distally tapered in essentiallythe same or mirror image relationship to each other. The distal sectionmay also have one or more tapered segments which have typical distallydecreasing tapers with substantially round transverse cross sections.

[0008] Preferably the flexible segment is disposed at a distal end ofthe distal section where it can perform the function of a shapeablemember. The flexible segment has a length typically ranging from about 1to about 12 cm, preferably about 2 to about 10 cm, although longersegments may be used. The flexible segment provides a controlledlongitudinal variation and transition in flexibility of the coresegment. A flexible body member having a proximal end and a distal endis typically disposed about and attached to the distal section of theelongate core member. A flexible body member, such as a helical coil,polymer jacket, or the like, surrounds and covers at least a portion ofthe distal section of the elongate core member. The proximal end of thehelical coil or flexible body typically is secured to the distal sectionof the elongate core member. Depending on the selected lengths of thehelical coil and the flexible segment or shapeable member, the junctionof the proximal end of the coil to the core may be at an intermediateposition on the distal section or may be at an intermediate position onthe flexible segment or anywhere in between.

[0009] In one preferred embodiment of a guidewire having features of theinvention, the distal section of the core member has at least oneflexible segment with at least two opposed tapered faces taperingdistally over the length of the flexible segment to a smaller transverseseparation. Optionally, the opposed tapered faces may be mirror imagesand parallel as well as distally tapered. In addition, the tapered facesmay have either a substantially straight or curved longitudinal profile.Other than the flexible segment, the construction of the guidewire issimilar to the guidewire discussed above with a flexible body memberdisposed about at least a portion of the distal section and is securedthereto. The proximal section of the elongate core member is nominallyround in cross section and preferably with a constant diameter and saidround cross section preferably extends distally to a proximal end of theflexible segment disposed on the distal section of the core. Theflexible segment may be disposed anywhere on the distal section, butpreferably is disposed at a distal end of the distal section, serving asa shapable member.

[0010] The taper geometry of the flexible segment may be modeledmathematically. Specific taper or face angles or contours may beselected in keeping with the principles and spirit of the invention toachieve optimum performance for specific usage requirements. These andother advantages of the invention will become more apparent from thefollowing detailed description of the invention when taken inconjunction with the accompanying exemplary drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0011]FIG. 1 is an elevation view, partially in section, of a guidewireembodying features of the invention.

[0012]FIG. 2 is an enlarged elevational view of a portion of the distalsection of the elongated core member of the guidewire shown in FIG. 1.

[0013]FIG. 3 is an end view of the embodiment of FIG. 2, shown as viewedfrom line 3-3 in FIG. 2.

[0014]FIG. 4 is an elevational view of an elongated core member for aguidewire having features of the invention.

[0015]FIG. 5 is a side elevation view of the embodiment shown in FIG. 4.

[0016]FIG. 6 is a end view of the embodiment of FIGS. 4 and 5, shown asviewed from line 6-6 in FIG. 5.

[0017]FIG. 6A is a transverse cross sectional view of the flexiblesegment of FIG. 5 taken at lines 6A-6A.

[0018]FIG. 7 is an elevational view of a portion of an elongated coremember for a guidewire having features of the invention.

[0019]FIG. 8 is a side elevation view of the embodiment of FIG. 7.

[0020]FIG. 9 is a end elevation view of the embodiment of FIGS. 7 and 8,shown as viewed from line 9-9 in FIG. 8.

DETAILED DESCRIPTION OF THE INVENTION

[0021]FIG. 1 is an elevational view of guidewire 10 which embodiesfeatures of the invention, and which includes an elongated core member11 with a proximal core section 12, a distal core section 13, and aflexible body member 14 which is fixed to the distal core section. Thedistal core section 13 has a tapered segment 15, a flexible segment 16which is distally contiguous to the tapered segment 15, a distal end 13a, and a proximal end 13 b. The distal section 13 may also have morethan one tapered segment 15 which have typical distally decreasingtapers with substantially round transverse cross sections. A guidewirehaving multiple continuous tapered segments in the distal section of theelongate core member is described in U.S. patent application Ser. No.08/868,764, filed Jun. 4, 1997 (Cornish, et al.) entitled STEERABLEGUIDEWIRE WITH ENHANCED DISTAL SUPPORT, which is hereby incorporated byreference in its entirety.

[0022] The core member 11 may be formed of stainless steel, NiTi alloysor combinations thereof such as described in U.S. Pat. No. 5,341,818(Abrams et al) which has been incorporated herein. Other materials suchas the high strength alloys as described in U.S. Pat. No. 5,636,641(Fariabi), entitled HIGH STRENGTH MEMBER FOR INTRACORPOREAL USE, whichis incorporated herein by reference, may also be used.

[0023] The core member 11 is optionally coated with a lubricious coatingsuch as a fluoropolymer, e.g. TEFLON® available from DuPont, whichextends the length of the proximal core section. The distal section 13is also provided with a lubricous coating, such as a MICROGLIDE™ coatingused by the present assignee, Advanced Cardiovascular Systems, Inc. onmany of its commercially available guidewires. Hydrophilic coatings mayalso be employed.

[0024] The length and diameter of guidewire 10 may be varied to suit theparticular procedures in which it is to be used and the materials fromwhich it is constructed. The length of the guidewire 10 generally rangesfrom about 65 cm to about 320 cm, more typically ranging from about 160cm to about 200 cm, and preferably from about 175 cm to about 190 cm forthe coronary anatomy. The guidewire diameter generally ranges from about0.008 in. to about 0.035 in. (0.203 to 0.889 mm), more typically rangingfrom about 0.012 in. to about 0.018 in. (0.305 to 0.547 mm), andpreferably about 0.014 in. (0.336 mm) for coronary anatomy.

[0025] The flexible segment 16 terminates in a distal end 18. Flexiblebody member 14, preferably a helical coil, surrounds a portion of thedistal section of the elongated core 13, with a distal end 19 of theflexible body member 14 secured to the distal end 18 of the flexiblesegment 16 by the body of solder 20. The proximal end 22 of the flexiblebody member 14 is similarly bonded or secured to the distal core section13 by a body of solder 23. Materials and structures other than soldermay be used to join the flexible body 14 to the distal core section 13,and the term “solder body” includes other materials such as braze,epoxy, polymer adhesives, including cyanoacrylates and the like.

[0026] The wire from which the flexible body 14 is made generally has atransverse diameter of about 0.001 to about 0.004 inch, preferably about0.002 to about 0.003 inch (0.05 mm). Multiple turns of the distalportion of coil may be expanded to provide additional flexibility. Thehelical coil may have a diameter or transverse dimension that is aboutthe same as the proximal core section 12. The flexible body member 14may have a length of about 2 to about 40 cm or more, preferably about 2to about 10 cm in length. The flexible body member 14 may also be madefrom a polymer. Polymers suitable for forming a flexible body member 14can include polyimide, polyethylene, polyurethane, TFE, PTFE, ePTFE andother similar materials. A flexible body member 14 in the form of ahelical coil may be formed of a suitable radiopaque material such asplatinum or alloys thereof or formed of other material such as stainlesssteel and coated with a radiopaque material such as gold.

[0027] The flexible segment 16 has a length typically ranging about 1 toabout 12 cm, preferably about 2 to about 10 cm, although longer segmentsmay be used. The form of taper of the flexible segment 16 provides acontrolled longitudinal variation and transition in flexibility (ordegree of stiffness) of the core segment. The flexible segment iscontiguous with the core member 11 and is distally disposed on thedistal section 13 so as to serve as a shapable member.

[0028] Referring to FIG. 2, the flexible segment 16 of guidewire 10 isshown in more detail. The flexible segment 16 is tapered distally bothin height and width and has a generally square cross section defined bya first pair of opposed tapered faces and a second set of opposedtapered faces. The first set of opposed tapered faces consists of a topface 25 and a bottom face 26, which taper distally together to a smallertransverse separation. The second set of opposed tapered faces consistsof a first side face 27 and a second side face 28 which taper distallytogether to a smaller transverse separation. Each of the tapered faces25-28 are substantially axially coextensive and extend from thetransition portion 24 of the distal section 13 to the distal end 18 ofthe flexible segment 16. Thus flexible segment 16 tapers to becomeprogressively narrower in both transverse directions as the distal end18 is approached. This results in a smooth decrease in cross sectionalarea and stiffness distally. Each of the tapered faces 25-28 has alongitudinal contour that is substantially straight. In addition, thetop face 25 is a mirror image of the bottom face 26 about thelongitudinal axis 17. The first side face 27 is a mirror image of thesecond side face 28 about the axis 17.

[0029] The short transition portion 24 is shaped to provide a generallycontinuous transition from the circular cross section of the distal end29 of the tapered segment 15 to the substantially square cross sectionof the proximal end 30 of the flexible segment 16. Referring to FIG. 3,the first set of opposed tapered faces 25 and 26 are substantiallynormal at any given transverse cross section to the second set ofopposed tapered faces 27 and 28. Or in other words, in any transversecross section of the flexible segment 16, the lines representing thesurfaces of the first set of opposed tapered faces 25 and 26 will besubstantially normal to the lines representing the second set of opposedtapered faces 27 and 28.

[0030] The multiple tapers or faces of the flexible segment 16 may beground simultaneously or as separate operations. A centerless grinderwith profile capabilities may be used to grind the tapers or facessimultaneously. A manual centerless grinding may be employed to createseparate tapers or faces in separate operations. Tapers or faces mayalso be formed by other means such as chemical means, e.g. etching, orlaser means.

[0031]FIGS. 4, 5 and 6 depict an alternative embodiment of a flexiblesegment 40 wherein one pair of opposed tapered faces taper distally to asmaller transverse separation. This results in a smooth decrease incross sectional area and stiffness distally over the length of theflexible segment 40. The flexible segment 40 is preferably integrallyformed with a tapered segment 41 of a distal core section 42. The firstopposed tapered face 43 and second opposed tapered face 44 slopedistally and incline towards the axis 45 of the segment 40. The opposedfaces 43 and 44 terminate distally at the distal end 46 of the flexiblesegment 40. The width of the distal end 46 can be the diameter of theproximal end 47 of the flexible segment 40. In the embodiment shown, theround cross section of the tapered segment 41 is continued in theflexible segment 40 except to the extent that the material of the core42 has been removed or shaped in order to form the first and secondopposed tapered faces 43 and 44. Thus, the side surfaces 48 and 49 ofthe flexible segment 40 may have a curved profile. The longitudinalcontours of each of the first and second opposed tapered faces aresubstantially straight, in addition to being mirror images aboutlongitudinal axis 45. In FIG. 6A a transverse cross sectional view ofthe flexible segment 40 taken at lines 6A-6A in FIG. 5 shows the curvedprofile of the side surfaces 48 and 49. In addition, the flattened shapeof the cross section is indicated by the major transverse dimension 49 aand the short transverse dimension 49 b of the flexible segment 40. Inthe cross section of FIG. 6A, the major transverse dimension 49 a issubstantially greater than the small transverse dimension 49 b.

[0032]FIGS. 7, 8 and 9 depict an embodiment of a flexible segment 50with two pairs of opposed faces which are generally coextensive in anaxial direction. The first pair of opposed faces consists of a firsttapered face 51 and a second tapered face 52. The second pair of opposedfaces consists of a first parallel face 53 and a second parallel face54. The first tapered face 51 and second tapered face 52 taper distallyto a smaller transverse separation with respect to each other such thatthe distance between the first tapered face 51 and the second taperedface 52 is greater at the proximal end 55 of the flexible segment 50than at the distal end 56 of the flexible segment.

[0033] The first parallel face 53 is substantially parallel to thesecond parallel face 54 along the length of the flexible segment 50except at the proximal end 55 of the flexible segment where the firstand second parallel faces terminate proximally at the first transitionsegment 57 and a second transition segment 58. The optional first andsecond transition segments 57 and 58 span the difference in transversedimension from the proximal end 55 of the flexible segment 50 to thedistal end 61 of the tapered segment 62 of the distal core section 63.Although the first and second tapered faces 51 and 52 have substantiallystraight longitudinal contours, these contours may also be curved. Thefirst and second transition segments 57 and 58 may also be curved so asto create a smooth transition at the proximal end 55 of the flexiblesegment 50.

[0034] While particular forms of the invention have been illustrated anddescribed, it will be apparent that various modifications can be madewithout departing from the spirit and scope of the invention.Accordingly, it is not intended that the invention be limited, except asby the appended claims.

What is claimed is:
 1. A guidewire comprising an elongate core memberhaving a proximal section and a distal section with the distal sectionhaving at least one flexible segment having a smoothly distallydecreasing cross sectional area and at least a portion where a majortransverse dimension is substantially greater than a small transversedimension.
 2. The guidewire of claim 1 wherein the proximal section ofthe elongate core member has a nominally round transverse cross sectionand the distal section of the elongate core member further comprises aproximal end and a distal end and the flexible segment is disposed atthe distal end of the distal section.
 3. The guidewire of claim 2further comprising a flexible body member having a proximal end and adistal end which is disposed about at least a portion of the distalsection of the elongate core member and wherein the distal end of theflexible body member is secured to the distal end of the distal sectionof the elongate core member.
 4. The guidewire of claim 2 wherein theflexible segment further comprises a pair of opposed tapered faceshaving longitudinal contours that are substantially straight.
 5. Theguidewire of claim 2 wherein the flexible segment further comprises apair of opposed tapered faces having longitudinal contours that arecurved.
 6. The guidewire of claim 2 wherein the flexible segment furthercomprises a pair of opposed tapered faces having substantially mirrorimage longitudinal contours.
 7. The guidewire of claim 2 wherein theflexible segment has a major transverse dimension that is substantiallyconstant along its length.
 8. A guidewire comprising an elongate coremember having a proximal section and a distal section with the distalsection having at least one flexible segment having two opposed facestapering distally to a smaller transverse separation and having anessentially rectangular cross sectional shape.
 9. The guidewire of claim8 wherein the proximal section of the elongate core member has anominally round transverse cross section and the distal section of theelongate core member further comprises a proximal end and a distal endand the flexible segment is disposed at the distal end of the distalsection.
 10. The guidewire of claim 9 further comprising a flexible bodymember having a proximal end and a distal end which is disposed about atleast a portion of the distal section of the elongate core member andwherein the distal end of the flexible body member is secured to thedistal end of the distal section of the elongate core member.
 11. Theguidewire of claim 9 wherein the opposed faces have longitudinalcontours that are substantially straight.
 12. The guidewire of claim 9wherein the opposed faces have longitudinal contours that are curved.13. The guidewire of claim 9 wherein the opposed faces havesubstantially mirror image longitudinal contours.
 14. The guidewire ofclaim 9 wherein the flexible segment has a major transverse dimensionthat is substantially constant along its length.
 15. A guidewirecomprising: a) an elongate core member having a proximal section and adistal section with the distal section having at least one flexiblesegment with a first pair of opposed tapered faces tapering distally toa smaller transverse separation and a second set of opposed taperedfaces which are axially coextensive with the first set of opposedtapered faces and which taper distally to a smaller transverseseparation; b) a flexible body member having a proximal end and a distalend disposed about at least a portion of the distal section of theelongate core member and secured to at least a portion thereof.
 16. Theguidewire of claim 15 wherein the proximal section of the elongate coremember has a nominally round transverse cross section and the distalsection of the elongate core member further comprises a proximal end anda distal end and the flexible segment is disposed at the distal end ofthe distal section.
 17. The guidewire of claim 16 wherein the distal endof the flexible body member is secured to the distal end of the distalsection of the elongate core member.
 18. The guidewire of claim 16wherein both sets of tapered faces have a longitudinal contour that issubstantially straight.
 19. The guidewire of claim 16 wherein both setsof tapered faces have a longitudinal contour that is curved.
 20. Theguidewire of claim 16 wherein a transverse cross section of any portionof the flexible segment is substantially square in shape.
 21. Theguidewire of claim 16 wherein the first set of tapered faces issubstantially normal to the second set of tapered faces.
 22. A guidewirecomprising: a) an elongate core member having a proximal section and adistal section with the distal section having at least one flexiblesegment with a first pair of opposed faces which taper distally to asmaller transverse separation and a second set of opposed faces whichare axially coextensive with the first set of opposed faces and whichare substantially parallel to each other; b) a flexible body memberhaving a proximal end and a distal end disposed about at least a portionof the distal section of the elongate core member and secured to atleast a portion thereof.
 23. The guidewire of claim 22 wherein theproximal section of the elongate core member has a nominally roundtransverse cross section and the distal section of the elongate coremember further comprises a proximal end and a distal end and theflexible segment is disposed at the distal end of the distal section.24. The guidewire of claim 23 wherein the distal end of the flexiblebody member is secured to the distal end of the distal section of theelongate core member.
 25. The guidewire of claim 23 wherein the firstset of opposed faces and the second set of opposed faces have alongitudinal contour that is substantially straight.
 26. The guidewireof claim 23 wherein the first set of opposed faces and the second set ofopposed faces have a longitudinal contour that is curved.
 27. Theguidewire of claim 23 wherein the second set of opposed faces have atransverse dimension greater than a transverse dimension of the firstset of opposed faces along a substantial length of the flexible segment.28. The guidewire of claim 23 wherein a transverse cross section of anyportion of the flexible segment is substantially rectangular in shape.29. The guidewire of claim 23 wherein the first set of opposed faces issubstantially normal to the second set of opposed faces.